Apparatus for igniting and operating gaseous discharge devices



June 1953 P. BERGER 2,837,697 APPARATUS FOR IGNITING AND OPERATINGGASEOUS DISCHARGE DEVICES Filed Jan. 5, 1956 Z Sheets-Sheet 1 @a/ 32/ 2yo W Mg June 3, 1958 P BERGER APPARATUS FOR IGNITING AND OPERATINGGASEOUS DISCHARGE DEVICES Filed Jan. 5. 1956 2 Sheets-Sheet 2 VVBWWWUnited States Patent O APPARATUS FUR IGNITlNG AND OPERATING GASEOUSDISCHARGE DEVICES Paul Berger, Chicago, ill., assignor to AdvanceTransformer Co., Chicago, 111., a corporation of Illinois ApplicationJanuary 5, 1956, Serial No. 557,550 12 Claims. (Cl. 315-138) Thisinvention relates generally to apparatus for providing the ignitingvoltage for two gaseous discharge devices from an A. C. source ofrelatively low voltage, and thereafter providing the proper operatingvoltages for the devices. More particularly this invention is concernedwith the construction of a so-called ballast for fluorescent lamps whichis characterized by a substantial decrease in the primary excitingcurrent decreasing the likelihood of burn-out under abnormal heatingconditions.

The principal object of the invention is the provision of apparatusreferred to above, and in the provision of such apparatus which will behighly efiicient and economical.

This invention comprises an improvement upon the basic structure ofapparatus described and claimed in U. S. Patents 2,558,293 and2,683,243. The former patent is one which discloses a ballast havingthree windings P, S and S connected end to end and mounted upon anelongate iron core with the primary in the center and the firstsecondary winding S spaced from the primary winding by means of amagnetic shunt, and with the second secondary winding S on the oppositeside of the primary winding coupled substantially closer to the primarywinding P than is the first secondary Winding. Two gaseous dischargedevices are connected across the windings of the transformer of theapparatus in such a way that they ignite seriatirn, the first devicebeing connected in series with a con-denser and together therewithconnected across the primary and first secondary windings in oneembodiment, and connected only across the first secondary winding S in asecond embodiment. In the first embodiment, the second discharge deviceis connected across both secondaries and in the second embodiment, thesecond gaseous discharge device is connected across all three windings.In both embodiments, the secondary windings are in open circuit voltagebucking relationship, but in the first the open circuit voltage of theprimary winding is additive to that of the first secondary winding S andin the second embodiment the open circuit voltage of the primary windingP is additive to that of the second secondary winding S In bothembodiments of said Patent 2,55 8,293, the energization of the primarywinding will initially result in voltage being provided only across thefirst gaseous discharge device to ignite it. With flow of current thevoltage of the winding S shifts its phase to provide a voltage additiveto those windings across which the second gaseous discharge device isconnected to ignite the same. Due to the high leakage reactance of thesecondary winding S current through the lamps is principally as in aseries connection through the lamps, condenser and secondary S Theapparatus herein uses the basic circuit of the above describedapparatus, as to both embodiments, and the gaseous discharge devicesherein are ignited and operated in the same way.

The second mentioned patent is an improvement on the first, in which thepatentee wound a part of the secondary winding upon the primary windingP to lower the voltage requirements of the winding S In this invention,an additional object is to decrease the leakage between the winding Sand the primary which decreases the number of turns required of thewinding S in order to achieve the desired starting and operatingvoltages, and to that end a part of the primary winding P, for example20% is closely coupled with the secondary winding S and for betterresults, a portion of the second secondary winding S may also be closelycoupled with the primary winding P.

The drawings accompanying this specification illustrate preferredembodiments of the invention in different forms, the invention beingapplied to the two different circuits of the Patent 2,558,293 abovereferred to, for the purpose of rendering the detailed explanationhereinafter set forth more understandable, and as well for complyingwith the patent laws.

To the extent practicable, the same characters of reference are usedthroughout the figures of the different forms of the invention, toillustrate and designate the same elements.

Fig. l is a top plan view of a transformer constructed in accordancewith the invention for use with the apparatus thereof with the windingsbeing shown in section.

Figs. 2 through 7 are electrical diagrams of the apparatus of theinvention showing different forms and variations which the inventionassumes, and all being capable of use with the transformer of Fig. 1.

In Fig. 1 there is illustrated a transformer 19 of socalled shell typeconstruction, the same having an iron core 12 providing elongate sides14, bridging ends 16 and 17 and three winding windows 18, 20 and 22 forreceiving therein the windings to be described. inwardly directedextensions 24 and 26 cooperate with an elongate central winding leg 28to provide shunts 30 and 32 having gaps 34 and 36. The ends 33 and 46)of the central winding leg 28 are matingly engaged in the bridging ends16 and 17 respectively, with the end 40 providing a bridging gap 42 ifdesired.

The winding window 18 is intended to have a first secondary windingdesignated S therein. The window 29 is intended to have either a part ofthe primary winding designated P therein, and in some cases a part ofthe second secondary winding S may also be disposed therein. The window22 may have either the entire second secondary S or a part therein, andalso has a part of the primary winding P therein.

Referring now to the various forms of the invention, in Fig. 2 there isillustrated a form of the invention in which the first gaseous dischargedevice is connected in series with a condenser and together therewithconnected across the primary and first secondary windings together, andthe second gaseous discharge device is connected across both of thesecondaries. Part of the primary is closely coupled to the secondsecondary winding, and part of the second secondary winding is closelycoupled to the primary winding.

Specifically, the primary winding consists of two parts designated P andP. Both parts are in series and connected together across the relativelylow voltage A. C. line 50. The right hand terminal of the primarywinding P, P is connected to the left hand terminal of a high leakagereactance secondary winding S at a junction 52. The second secondarywinding is formed of two parts S and 3,, connected in series, and theleft hand terminal of the second secondary winding S S is connected tothe right hand terminal of the first secondary winding S at a junction54. A gaseous discharge device L which may be a fluorescent lamp, isconnected achieve unusually good results,

o in series with a condenser C and together therewith connected acrossthe primary winding P, P and'the first secondary winding S that is fromone side of the line to the junction 54.

There is a second gaseous discharge device L connected across bothsecondary windings, that is, from the junction 52 to the right handterminal of the winding S The open circuit instantaneous voltages of theprimary winding P, P and the first secondary winding S are additive. Theopen circuit instantaneous voltages of the first secondary winding 5;and the second secondary winding S S are in opposition. The dischargedevice L ignites first, and flow of current through S causes a phasereversal giving a component of voltage additive to the open circuitvoltage of second secondary winding S S causing seriatim ignition of thesecond discharge device L Thereafter, since winding S has highreactance, current will prefer to flow in series through the dischargedevices L L the condenser C, and the second secondary winding S S withthe reactive relationship between the condenser C and second secondarywinding S S etermining the power factor.

A portion of the primary winding designated P is closely coupled to theportion of the second secondary winding which is designated S Likewise aportion of the second secondary winding which is designated S is closelycoupled to that portion of the primary winding which is designated P. Inpractise, a small coil is either wound on top of or alongside each ofthe coils which would otherwise be the primary and second secondarywindings, and the connections are made to the small coils so thatcircuit-wise they are respective parts of the primary and secondarywindings. Thus, although the primary winding of Fig. 2 is formed of twocoils P and P, the term winding will be used to collectively designateboth as P, P. Likewise, the second secondary winding of Fig. 2 is formedof two physically separated coils S and S but for convenience, the wordwinding will also be used collectively to designate both, composed ofthe two coils or parts.

In describing the structure of Fig. 2, it may therefore be said that aminor part of the primary winding is closely coupled to a major part ofthe second secondary windings, and a minor part of the second secondarywinding is closely coupled to the major part of the primary winding.

The structure of Fig. 3 is similar to that of Fig. 2, except that thesecond secondary winding is not formed of two parts, and hence there isonly one coil designated S which will be disposed in window 22 togetherwith the minor part P of the primary winding P, P.

The operation of the apparatus of Figs. 2 and 3 is quite similar. Theexistence of an end gap such as shown at 42 in Fig. 1 is not alwaysdesirable because of the increase in primary excitation current which itcauses. Primary exitation current adversely attects heating andefficiency, but the eventual results of increased lighting throughimproved wave shape are desired through the use of the end gap.

By placing a portion of the primary winding in close coupledrelationship with the second secondary winding and cutting down theleakage between the two windings, at least as to that portion P or" theprimary which is closely coupled, the voltage available from the secondsecondary winding is increased. Many adjustments of windings andplacement of the g can be made to wheat materially increasing the costor size of the apparatus, Thus, the placement of the part P in closecoupled relationship with the winding S can eliminate the need for anend gap, thereby eliminating the likelihood or" high primary currentunder abnormal conditions. The wave shape is improved, and likewisebetter balance of currents between lamps is achieved, especially by-theuse of the structure of Fig. 2. t

The structure of Fig. 4 is quite similar to that of Fig.

3,"eXcept that th'c'secondary winding S is tapped into the secondsecondary winding c at 56. In this manner, although the secondarywindings S and S are in open circuit instantaneous voltage opposition,the portion of the winding S to the left of the tap $56 can be usedtoprovide a starting voltage for the discharge device L additive to thevoltage of the winding 8 The structures of Figs. 5, 6 and 7 operate thesame way as the structures of Figs. 2, 3 and 4 respectively. Thedifference lies in the arrangement of the discharge device in thecircuit and the open circuit instantaneous voltage relationships betweenthe windings. Where in the above described structures the device L wasconnected across the primary windingand first secondary windingtogether, in Figs. 5, 6 and 7 the discharge device L is connected acrossthe winding S alone, that is, in series with condenser C and togethertherewith from junction 52 to junction 54 or from junction 52 to tap 56in Fig. 7. Likewise, instead of being connected cross the secondarywindings only, as in Figs. 2, 3 and 4; in Figs. 5, 6 and 7, the secondgaseous discharge device L is connected across all of the windings, thatis, from the left'hand end of the primary winding P, P to the right handend'of the second secondary winding S S (or S alone).

in Figs. 5, 6 and 7 the secondary windings are still in open circuitvoltage opposition to one another, but the open circuit voltage of theprimary winding is additive to that of the second secondary winding, sothat the first secondary winding S alone is required to providesuificicut open circuit voltage to ignite discharge device L Of coursein Fig. 7 it is assisted by a part of the winding S 7 As previouslystated, it has been found that the proportion of the minor parts of thewindings P, P and S S to the whole which seem to give the best resultsis about 20%. Likewise, the starting aid of the tapped secondary windingS of Figs. 4 and 7 is about best when the tap 56 includes about 20% ofthe total winding to the left of the tap as viewed in the drawings.

In a circuit like Fig. 2, using the form of core of Fig. 1 two instantstart watt lamps were successfully ignited and operated when the variouswindings and their parts were made up as follows:

With an end gap:

S 3100 turns of #32 wire' S 1500 turns of #28 wire S 400 turns of #28wire P, 410 turns of #23 wire P, 50 turns of #23 wire It was found thatthe end gap could be eliminated by merely shifting the number of turnson the parts of the primary winding. P was decreased to 360 turns, and Pwas increased to turns. The width of the winding leg 28 was 1 inch andother dimensions proportional.

It is believed that no further explanation is required, other than topoint out that the results which are achieved, namely low primaryexciting current, good wave shape, and excellent current balance betweenthe lamps, are directly attributable to' the structures described,irrespective of whether the theoretical explanation of operation iscorrect or not. It is desired to be limited in the structure only by theclaims appended hereto.

What it is desired to claim is:

1. Apparatus for igniting and providing the operating voltages ofgaseous discharge devices comprising: a source of low voltage A. C.current, a transformer having a primary winding connected across thesource and having' first and second end terminals, a first secondarywind- 'ing having first and second end terminals with the first firstandfsecond end terminals with'the' second end terminal of said firstsecondary winding connected to said second secondary winding at a pointother than said second terminal thereof, an elongate iron core mountingall of the windings with the first secondary winding disposed on one endof the core and there being a shunt between the said first secondarywinding and the remainder of the windings, a

first gaseous discharge device having a condenser connected in seriestherewith and connected from the first terminal of the second secondarywinding to one of the first and second terminals of the primary winding,a second gaseous discharge device connected from the second terminal ofthe second secondary winding to the other of said first and secondterminals of said primary winding, and the open circuit voltagerelationship of the secondaries being in opposition, the secondsecondary winding being disposed on the end of said core opposite thefirst secondary winding, with the major portion of the primary windingphysically disposed between the two secondary windings on said core andcloser coupled with the second secondary winding than the first, and aminor portion of the primary winding closely coupled with the secondsecondary winding and physically separated from the major portion ofsaid primary winding, the coupling between the minor portion of theprimary winding and the second secondary winding being substantiallycloser than the coupling between the major portion of the primarywinding and the second secondary winding.

2. A structure as described in claim 1 in which there is a secondmagnetic shunt between the major portion of primary winding and thesecond secondary winding, the minor portion of said primary windingbeing on the same side of said second shunt as said second secondarywindmg.

3. A structure as described in claim 1 in which the point of said secondsecondary winding comprises its first terminal.

4. A structure as described in claim 1 in which the point of said secondsecondary winding comprises a tap electrically closer to its first thanits second terminal.

5. A structure as described in claim 1 in which the first gaseousdischarge device has an end thereof connected to the first terminal ofthe primary winding, and the second gaseous discharge device has an endthereof connected to the second terminal of the primary winding.

6. A structure as described in claim 1 in which the first gaseousdischarge device has an end thereof connected to the second terminal ofthe primary winding, and the second gaseous discharge device has an endthereof connected to the first terminal of the primary winding.

7. Apparatus for igniting and providing the operating voltages ofgaseous discharge devices comprising: a source of low voltage A. C.current, a transformer having a primary winding connected across thesource and having first and second end terminals, a first secondarywinding having first and second end terminals with the first endterminal connected to the second terminal of the primary winding, and asecond secondary winding having first and second end terminals with thesecond end terminal of said first secondary winding connected to saidsecond secondary winding at a point other than said second terminalthereof, an elongate iron core mounting all of the windings with thefirst secondary winding disposed on one end of the core and there beinga shunt between the said first secondary winding and the remainder ofthe windings, a first gaseous discharge device having a condenserconnected in series therewith and connected from the first terminal ofthe second secondary winding to one of the first and second terminals ofthe primary winding, a second gaseous discharge device connected fromthe second terminal of the second secondary winding to the other of saidfirst and second terminals of said primary winding, and the open circuitvoltage relationship of the secondaries being in opposition, the majorportion of the second secondary winding being disposed on the end ofsaid core opposite the first secondary winding, with the major portionof the primary winding physically disposed between the first secondarywinding and the said major portion of the second secondary winding, andthere being a minor portion of the primary winding closely coupled withthe major portion of the second secondary winding and a minor portion ofthe second secondary winding closely coupled with the major portion ofthe primary winding.

8. A structure as described in claim 7 in which there is a second shuntsubstantially narrower than said first shunt, and disposed between themajor portions of the primary and second secondary windings.

9. A structure as described in claim 7 in which the point of said secondsecondary winding comprises its first terminal.

10. A structure as described in claim 7 in which the point of saidsecond secondary winding comprises a tap electrically closer to itsfirst than its second terminal.

11. A structure described in claim 7 in which the first gaseousdischarge device has an end thereof connected to the first terminal ofthe primary winding, and the second gaseous discharge device has an endthereof connected to the second terminal of the primary winding.

12. A structure as described in claim 7 in which the first gaseousdischarge device has an end thereof connected to the second terminal ofthe primary winding, and the second gaseous discharge device has an endthereof connected to the first terminal of the primary winding.

References Cited in the file of this patent UNITED STATES PATENTS2,685,662 Feinberg et al. Aug. 3, 1954 2,716,205 Feinberg et a1 Aug. 23,1955 2,730,656 Cornell Jan. 10, 1956

